Basically a medicament delivery device is a device that is simple to use without the need of performing many steps when an individual has to administer a dose of medicament by himself/herself. This requires a solution where the medicament delivery device can be kept as pre-assembled and ready as possible, in order to deliver the medicament in a measured dose, with the minimal number of further manual operations or actions. Thus, to minimize the number of steps needed, in order to perform a medicament delivery, some known prior art devices only need to be actuated against the delivery area, without the need of manual actuation, by pressing a button or the like, which causes the medicament delivery device to perform the delivery. There is however a common need for a medicament delivery device which is very easy to use and which can reliably deliver a set dose of a medicament, in order that the device may be used for self-delivery or by other un-skilled personnel. For example, a person susceptible to anaphylactic shock will normally carry an auto-injector device, pre-charged with adrenalin, to allow an emergency injection of that drug in the event that the patient is suffering from anaphylactic shock. In such conditions, speed is of essence and it may be necessary for a completely un-skilled person to use the injection device to administer the injection. Thus an injection delivery procedure which is easily facilitated and intuitive is highly required.
In U.S. Pat. No. 6,893,420 is disclosed a device arranged with a locking means for locking a latch that prevents the automatic penetration and injection means from being released before mixing of the medicament is finished. Thereby the device of U.S. Pat. No. 6,893,420 provides a pre-assembled medicament delivery device that has great storage facilities and at the same time is easy to use. However, a disadvantage of this prior art solution is that it sometimes is unreliable and may unintentionally be actuated, either by mishap' or by improper usage. One important safety aspect when handling a medicament delivery device is the locking of the injection actuator, before the medicament delivery device is ready for use.
One such device is disclosed in U.S. Pat. No. 6,210,369 describing an injector device having features that prevents unintentional operation of the injector. The penetration and injection is performed manually, by pressing an actuator i.e. a button, thereby enabling the needle to penetrate the injection site. When the injection has been performed the injector is withdrawn, whereby a needle shield extends in a locked position surrounding the needle. As will be noted, a disadvantage with this solution is the extra operation needed to perform an injection. This makes the operation of the device less intuitive; the user needs to find out how to remove a cover over the button, in order to activate the automatic medicament delivery device. This may cause unnecessary delays, which could be harmful or even critical for a patient to be treated.
There is therefore a need for an arrangement that can provide both improved safety handling as well as improved medicament handling. I.e. there is a need for an arrangement where a manually activation for triggering a medicament delivery cannot be performed until a protective cap covering a delivery member is removed. Thus, as can be noted, human handling aspects of the medicament delivery device are crucial and there are several rationales for improving existing solutions.